UMass Extension Landscape Message #22
September 2, 2005

Quick Info Menu ------------------------------- ENVIRONMENTAL DATA REGIONAL NOTES - Cape Cod - Southeast - East - Central - Pioneer Valley - Berkshire PHENOLOGY WOODY ORNAMENTALS - Insects - Diseases - Lab Report - Weeds TURFGRASS - Insects - Diseases - Weeds INFO RESOURCES DIAGNOSTIC SERVICES Use this menu to instantly jump to any portion of the message!

The LANDSCAPE MESSAGE is an educational newsletter intended to guide landscape, nursery and urban forestry professionals in identifying pests in the landscape, monitoring their development, planning management strategies and creating site-specific records for future management reference. This issue has been updated to provide timely pest management information and the latest regional news and environmental data throughout Massachusetts. During the months of July, August and September, the LANDSCAPE MESSAGE will be updated on a bi-weekly basis. The next update will be available in two weeks on Friday, September 16, 2005. Missed a previous message? Visit the Landscape Message Archive. Interested in additional turf-oriented content? UMass Extension Turf Program Management Updates

ENVIRONMENTAL DATA

The following growing degree day (GDD) and precipitation data was collected for the two-week period from August 18 through August 31, 2005 . Soil temperature and phenological indicators were observed on August 31, 2005. Accumulated GDDs represent the heating units above the 50° F baseline temperature collected via our instruments since the beginning of the current growing season. This information is intended for use as a guide for monitoring the developmental stages of pests in your location and planning management strategies accordingly.

REGIONAL NOTES

Cape Cod Region (Barnstable) - General Conditions: Finally, the Cape received some needed rainfall on August 29. This is the first significant precipitation since early June. At times the rain came down so hard that it ran off of the hydrophobic soil surfaces but enough soaked in to give some relief to drought stressed plants. Goldenrod and other late summer perennials are brightening the landscape. Pests/Problems:. Water stress is the number one problem for landscape plants that are not under irrigation. Many seriously wilted rhododendrons appreciated the soaking rain of 8/29, but the Cape needs to have regular rainfall to offset the damage that has occurred to shallow rooted trees and shrubs. Fall webworm webs are getting quite large. Wasps and yellow jacket colonies are also getting large. Many complaints of ground nesting wasps have come into the office. Unirrigated turf is completely dormant.

Southeast Region (Hanson) - General Conditions: Warm, humid weather and much needed rain brings August to a close. Prior to this rain soils were like powder, and trees were starting to show premature fall color. Hanson received about 4 inches of rain from August 23-28. Soils are moderately moist. Many oaks that were defoliated by caterpillars earlier this past spring have not fully recovered and look poor. Albizia julibrissin, Rose-of-Sharon, Hydrangea paniculata, Hydrangea quercifolia (Oakleaf hydrangea), Coreopsis 'Moonbeam', Joe-pye-weed, Rudbeckia trilobum, Rudbeckia 'Goldsturm', Echinacea purpurea, Corydalis lutea, Nepeta, Heliopsis 'Summer Sun', Lobelia cardinalis, Lobelia syphilitica, Lobelia hybrids, Hibiscus 'Copper King', Ironweed, and Phlox paniculata are in full bloom. Goldenrod and ragweed are in bloom. Pollen from ragweed may cause allergies in some people but goldenrod is often mistakenly blamed. Viburnum trilobum fruit is starting to turn color (gold/red). Pests/Problems: Sycamore lacebug was found on white oak in Hanson. Pieris lacebug, earwigs, ticks, slugs, snails, and mosquitoes are all active. Some crabapple trees have been defoliated by apple scab. Powdery mildew is prevalent on a wide range of plant material such as sycamore, garden phlox, lilac, dogwood. Anthracnose is evident on sycamore, maples, and other plants. Black locust foliage is turning brown due to locust leaf miner.

East Region (Boston) - General Conditions: No report.

Central Region (Boylston) - General Conditions: No report.

Pioneer Valley Region (Amherst) - General Conditions: The weather was mild and dry the first week, while the second week continued mild but with regular rainfall. Foliage is mature and green on most trees and shrubs, as fall color is beginning to show up on sumac. Pests/Problems: Leaf spots and yellowing accompanied by early leaf loss are evident on a number of trees and shrubs. Gray-green to yellow leaves that are often highly distorted is a good indication that powdery mildew has infected the foliage.

Berkshire Region (Great Barrington) - General Conditions: Until recent rains, soil root zones were getting quite dry. Soil moisture currently is fair but with heavy rains projected for today - fallout from hurricane Katrina - that could change. Turfgrass is looking good and recovering well from recent dry conditions. Overall, this has been a very good growing season, and landscapes have appeared lush, except for a short drought period in late July and early August. Pests/Problems: Early blooming herbaceous perennials are looking ratty as a result of various foliar blights. Powdery mildew is prominent on susceptible hosts. Insect populations remain at low levels. The Japanese beetle population seemed less than usual this year. Slugs, ticks, and fall webworm are the only prominent pests at this time.

PHENOLOGY

The phenological indicators are a visual tool for correlating plant development with pest development. The following are the indicator plants and the stages of bloom observed for this period:

CAPE COD REGION - Roberta Clark, Horticulturist for Barnstable County, Barnstable.

SOUTHEAST REGION - Deborah Swanson, Horticulturist for UMass Extension in Plymouth County, Hanson.

EAST REGION - James R. Allen, Horticulturist and Greenhouse Manager for UMass Biology Department, Boston.

CENTRAL REGION - Joann Vieira, Superintendent of Horticulture, Tower Hill Botanic Garden, Boylston.

PIONEER VALLEY - Dan Gillman, Plant Pathologist, Urban Forestry Diagnostic Lab, UMass, Amherst.

BERKSHIRES - Ron Kujawski, Specialist, UMass Extension Landscape, Nursery & Urban Forestry Program, Amherst.

WOODY ORNAMENTALS

INSECTS

The hot and humid weather continues to drive lacebugs and warm-season spider mite populations. Infested plants in sunnier locations are experiencing greater injury, overall.

Fall webworm - The webs have been becoming obvious for the past month. When found in small numbers and at reasonable heights, they can be pruned away and destroyed, with the caterpillars inside.

Hymenopteran Caterpillars (Sawflies):

Redheaded Pine Sawfly - This yellow caterpillar with black spots and a rust-colored head capsule will become active soon. Treat young larvae with an insecticidal soap spray or treat caterpillars of all ages with a product that contains spinosad.

Dogwood Sawfly - This yellow caterpillar with black spots is usually covered with a dense white pubescence that gives it the appearance of a bird dropping. Larger populations that go untreated can cause much defoliation. When found in considerable numbers, treat with a spinosad product.

Beetles:

Viburnum Leaf Beetle - Adult beetles are no longer active. Look for eggs along the bare twigs which results in a ‘sandpaper’ texture. Visit the Cornell web site, http://www.hort.cornell.edu/vlb/index.html , for current information on this pest. Report any new findings in MA to Robert Childs, rchilds@psis.umass.edu, 413-545-1053.

Japanese beetle activity is seriously winding down for this year.

Piercing-Sucking Pests:

Spider Mites:

• Inspect the needles and stems of conifers now for injury from spruce spider mite. Now that the hot and humid weather has been here for a while, this pest remains in its summer dormancy but will return by the end of August and can be active well into the fall. Horticultural oil sprays (at the summer rate) can be effective once they return to feed on the plant.
  
• Two-spotted spider mite (one of the warm-season mites) is now very active on a wide range of host plants. Warm season mites prefer, and thrive, during hot weather. Their rate of development is greatly accelerated by the heat; and at the same time, predatory mites often leave the host plant and go into summer dormancy in the leaf litter or mulch. This gives spider mite populations the potential to explode in numbers and to create much plant injury in a short amount of time. Continue to monitor on a regular basis, and treat increasing populations before they become too large. Horticultural oil sprays used at the summer rate can be quite effective, as are the new mite growth regulator products. Avoid the overuse of chemical pesticides; spider mites are quite adept at developing pesticide resistance.

Hemlock Woolly Adelgid (HWA) - This pest remains in its summer dormancy, and the tiny nymphs are settled along the stems at the base of the needles. Feeding will cease until mid-October. Horticultural oils can still be applied at the summer rate when the correct weather conditions prevail; avoid very hot and humid days for oil applications.

Andromeda lacebug remains extremely active. Inspect leaf undersides of Japanese andromeda for the activity of this pest. Treat the plant with a soil-applied systemic treatment of imidacloprid, or spray the leaf undersides with an insecticidal soap. Pyrethroid insecticides are also labeled for this pest.

Azalea Lacebug remains extremely active. Plants that are in sunnier locations can be severely damaged by this pest. (See Andromeda Lacebug above for recommendations.) Untreated plants in sunny locations can have foliage with a bleached appearance by mid to late August.

Scale Insects:

Armored Scales - A group of scale insects characterized by a hard, convex covering over their bodies, such as pine needle scale, euonymus scale , juniper scale and white prunicola scale can be monitored now using a piece of black electrical tape that has been repeatedly daubed on the stems; the tiny euonymus scale crawlers will appear as orange spots on the tape. Treat with a horticultural oil spray (summer rate) when plant phenology and correct weather conditions prevail.

Soft Scales:

• Cottony camellia scale (a.k.a. cottony taxus scale) remains active. Inspect leaf undersides for the nymphs. Females, when present, are tan-colored and round with an elongate and white egg-sac attached to their covering. When they are present in large numbers, this pest can greatly diminish plant growth and also be responsible for much unwanted sooty mold.

Leaf Miners:

Locust leafminer remains extremely active. Black locusts in most locations now appear as if swept by fire from this pest’s feeding. Nothing can be done now.

Wood Borers:

Dogwood Borer - The adult moths remain active. Pheromone traps are available for this pest. Keep flowering dogwood free of wounds from mowers and line trimmers, which encourage invasion by this insect. Treat infested trees in August and early September with a trunk/branch spray of entomopathogenic (beneficial) nematodes.

Rhododendron Borer - This is another clear-winged moth caterpillar that is a wood borer and a close relative to the dogwood borer (Sesiidae Family). Inspect around the base of rhododendrons, on the ground, for coarse sawdust that has been expelled by the caterpillar boring in the shoot. Physically prune out and destroy infested shoots or use a coarse spray of entomopathogenic nematodes.

Reported by Robert Childs, Entomologist, UMass Extension Landscape, Nursery and Urban Forestry Program, Amherst

DISEASES

Powdery mildew fungi are now visible as a dusty, gray to white spots/blotches on horsechestnut, phlox, dogwood, lilac, sycamore leaves as well as rose leaves and flower buds in the Amherst area. Once established on plants, powdery mildews grow superficially on both upper and lower leaf surfaces as well as green shoots and flower buds. They are obligate parasites and derive sustenance only from living host plants. They do this using minute, tube-like structures (haustoria) that penetrate the epidermal cells and draw out material they need to survive. Spherical, black fruiting structures (cleistothecia) are becoming visible with a hand lens on the underside of infected leaves in the dusty, gray mycelia. Generally, the damage caused by powdery mildew is of minor consequence to healthy plants and does not warrant chemical control if unsightliness is not a critical concern. If chemical control is desired, there are a number of unconventional applied materials including summer horticultural oil, commercial baking soda preparations (sodium bicarbonate and potassium bicarbonate), anti-transpirants, as well as a number of conventional fungicides. Chemical spray programs are most effective when begun just as symptoms of powdery mildew begin to show. Once powdery mildew is extensive on the plant, there is little benefit from chemical control that season. Applications need to coat both surfaces of all susceptible plant parts to prevent infection. Spray on a regular schedule, and repeat more often during warm, humid weather.

Cedar-apple rust is visible as reddish-yellow spots on susceptible hawthorn, apple and crab apple leaves. Many of the undersides of the reddish-yellow spots have tiny tube-like fruiting structures extending from infected leaves. From now to leaf fall, spores are wind-carried from the apple leaves and, when conditions are wet for several hours duration, they infect green shoots and needles of junipers. Pea-sized to 2 inches diameter round, brown galls develop on susceptible juniper needles and twigs between 12 and 20 months after infection. The best long-term approach to manage this disease is to grow cedar-apple rust resistant apple and juniper varieties. Also, prune dormant galls on juniper during the summer, fall, winter and very early spring (before jelly-like horns form). Avoid growing susceptible junipers close to apples. The time to apply fungicides to protect high value apples from cedar-apple rust has passed for this season. Fungicide protection of eastern red cedar and Rocky mountain junipers is seldom performed, but if it were desired, it would be from now through September when there are extended wet periods.

Horsechestnut (Guignardia) leaf blotch is evident as irregularly shaped orange-brown blotches on infected leaves. As the summer progresses the impact of the disease is often more noticeable, but chemical intervention at this time for this season is of little benefit. Likewise, it has been noted that horsechestnut that suffer repeated severe infections continue to grow vigorously in spite of Guignardia leaf blotch.

Dogwood anthracnose is visible as brown-tan spots/blotches as well as some shoot blighting. Remove and dispose of dead leaves, twigs and branches to reduce anthracnose inoculum in infected trees. Dogwoods receiving good cultural care are better able to limit the extent of dogwood anthracnose damage. Water during dry periods and maintain 2-3 inches of composted bark mulch over as much of the root area as possible. At this time, a fungicide application may be beneficial to protect the flower buds from infection during cool wet weather in the fall. Next spring begin applications as buds break open, when bracts have fallen and four weeks later. If dogwood anthracnose is a persistent problem consider planting one of the many resistant cultivars of Cornus florida and C. kousa now commercially available.

Ramorum Blight, also known as Sudden Oak Death (SOD) - Since 1995, oaks and tanoaks have been dying in the coastal counties of California. Since then, other types of plants have been found to be infected or associated with this disease, referred to as Sudden Oak Death, ramorum leaf blight or ramorum dieback, or by regulation as Phytophthora ramorum. SOD was first seen in 1995 in Mill Valley ( Marin County) on tanoak. Since that time, the disease has been confirmed on various native hosts in fourteen coastal California counties (Marin, Santa Cruz, Sonoma, Napa, San Mateo, Monterey, Santa Clara, Mendocino, Solano, Alameda, Contra Costa, Humboldt, Lake and San Francisco), and in Curry County, Oregon. Research being conducted by the Agriculture Research Service, US Forest Service, universities and others is under way to better identify hosts, methods of detection and effective treatments. Currently, 64 plants are regulated, two of which at the genus level (Camellia and Rhododendron). There are no chemical treatments currently available to eliminate the disease in nursery stock.

Status of Phytophthora ramorum Monitoring Surveys. The 2005 National Nursery Survey is underway. As of August 24, forty-eight states have reported compliance or national survey results; 4,226 nurseries have been reported visited and 106,118 samples collected. Fifty-one positives sites in seven states have been identified through national survey or Federal order and annual cleanliness compliance surveys. Outside of the three regulated west coast states, eight national survey positives have been confirmed. Georgia reports four positive nurseries; Louisiana reports two positives nurseries; and Tennessee reports one positive nursery and, as of this week, South Carolina reports one positive nursery. In the regulated states, California has found 23 positive nurseries during their Federal Order compliance surveys and annual cleanliness surveys. Oregon has identified 11 positive nurseries during their Federal Order and compliance surveys. Washington has reported nine national survey positive sites.

The US Forest Service and states are conducting nursery perimeter and general forest detection surveys in 38 states during 2005. As of August 3, USFS reports 390 nursery perimeter surveys in 28 states with 932 samples collected; results are available for 246 samples and all are negative. USFS reports 303 general forest surveys have been conducted in 27 states; 661 samples have been collected. There are no confirmed positives based on 128 results.

There was one new positive in the Eastern Region in the last three weeks. APHIS confirmed that a camellia located at a wholesale nursery/broker in Jasper County, South Carolina was positive for P. ramorum. This is the first report of a positive nursery in South Carolina in 2005. The nursery is part of a chain of nursery dealers. Another chain location, in Norcross, Georgia, tested positive earlier this year. In the Western Region during the last three weeks, three nurseries were confirmed as infested with Phytophthora ramorum—one in Oregon and two in Washington State. The Oregon nursery is located in Washington County and the pathogen was found on a rhododendron. It is a retail nursery/landscape company. In Washington, P. ramorum was identified at a Pierce County nursery on a rhododendron as well as at a retail nursery in Skagit County also on a rhododendron.

Dan Gillman, Plant Pathologist, based in the Urban Forestry Diagnostic Lab at UMass, Amherst.

WEEDS

No report: Visit the Landscape Message Archive for previous messages.

TURFGRASS

Insects:

We have been sampling for grubs in several areas throughout southern New England and find that grubs in several locations are fairly well developed. In general we are seeing late, first instars and very healthy second instars (medium sized larvae). The rains that are currently falling will mask damage for a while, but it would be wise for turf managers to get out and take a look now. It appears that most eggs have hatched by now, and grub activity will increase as the little monsters continue to eat and grow larger. The bigger they are, the more difficult it is to manage them, so look now and determine whether you have areas that are under attack.

Rescue treatment options at this point include (in no particular order):

• trichlorfon (Dylox™) - Very fast acting, will kill what it is going to kill within one to three days. Dylox™ is very mobile, so do not use it on sandy soils or near surface water or before rain is forecast. It is very sensitive to high pH. Dylox™™ cannot be used on school grounds that come under the auspices of the School IPM laws in Massachusetts.
• carbaryl (Sevin™) - Relatively fast acting, very inconsistent. Sometimes it works, and sometimes it doesn't! Sevin™ is very toxic to bees and wasps, so do not use near plants that are flowering or where bees or wasps are foraging.
• chlothianidin (Arena™) - This is a relatively new compound related to Merit™. The manufacturer claims that it can be used as a rescue treatment, but we have not had the material in field trials to test that concept. So let the buyer beware.
• halofenozide (Mach 2™) - Again the manufacturers claim this product can be used later in the season than Merit™. But halofenozide interferes with the grub’s ability to molt. If grubs have already molted to the third instar (which many will do soon), no benefit would be gained from applying Mach 2™. Personally, I think it is too late this year.
• Nematodes, specifically Heterorhabditis bacteriophora - These nematodes are available under several trade names and sometimes reduce grub populations. See messages in the archives from spring 2004, where the benefits and drawbacks of using nematodes was discussed. Once grubs approach full size, it is more difficult for the nematodes to be effective. So we are running out of time in many locations. Also note that Albrecht Koppenhoffer (my colleague at Rutgers University) reports that HB nematodes are more likely to be effective against Japanese beetle grubs and much less likely to be effective against the other species many of you are dealing with.

Remember, any grub treatment must be wtered in thoroughly.

Pat Vittum, Professor, Turf Entomology Department of Plant, UMass, Amherst.

Weeds: No report: Visit the Landscape Message Archive for previous messages.

New England Guide to Weed Control in Turfgrass - The updated 2005 New England Guide to Weed Control in Turfgrass is now available. It contains extensive information about currently registered turf herbicide products, including specifics on application, timing and environmentally responsible use. The guide is available as a free, downloadable PDF file in the Online Publications section of http://www.umassturf.org

Don't forget to visit the UMass Extension Online Weed Herbarium!

UMass Extension’s Turf Management Guide and IPM Facts: For more information about the pests mentioned in this message, you will need to refer to the following publications: the Professional Guide for IPM in Turf for Massachusetts, 2003-2004 edition and Turf IPM Facts . Call (413) 545-2717 to order these publications from the UMASS Extension Bookstore.

DIAGNOSTIC SERVICES

UMass Laboratory Diagnoses for Turf and Landscape Problems: Accurate diagnosis for a turf or landscape problem can often eliminate or reduce the need for pesticide use. The UMass Extension Urban Forestry Diagnostic Laboratory is available to serve commercial landscape contractors, turf managers, arborists, nurseries, and other green industry professionals. It provides woody plant disease analysis, woody plant and turf insect identification, turfgrass identification, landscape and turf weed identification and offers a report of pest management strategies that are research based, economically sound, and environmentally appropriate for the situation. Send specimens and payment made payable to the University of Massachusetts to Urban Forestry Diagnostic Lab, 160 Holdsworth Way, Holdsworth Natural Resources Center, UMass, Amherst, MA 01003. The fee for a woody plant disease analysis is $50.00. All insect, weed, and turfgrass identification samples are $25.00 each. For complete information and instructions on how to send specimens, visit the Urban Forestry Diagnostic Lab page.

Turfgrass disease samples should be directed to the UMass Turf Disease Diagnostic Lab . This service is available ONLY to green industry professionals such as landscapers, lawn care companies, and golf course managers. For more info specifically on turf disease diagnostics, visit the Disease Diagnostics page at www.umassturf.org .

NEXT UPDATE: The next issue will be available in Friday, September 16, 2005.

This message is produced by the UMASS Extension, Landscape, Nursery and Urban Forestry Program. The copy is prepared by Anna Greene from data and reports provided by the staff and faculty of the UMass Landscape, Nursery and Urban Forestry Program and the UMASS Extension Turf Program as well as cooperating horticulturists and Green Industry professionals. The text is adapted for access via the internet by Jason Lanier and made available to subscribers via electronic transmittal by Ellen Weeks.

DISCLAIMER. This message is intended for commercial use. UMASS Extension assumes no liability for recommendations. The use of trade names does not imply endorsement. Similarly, there may be other products you prefer to use.

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